Method for manufacturing a photomask

ABSTRACT

A method for manufacturing a photomask based on design data includes the steps of forming a figure element group including a figure element in a layout pattern on the photomask and a figure element affecting the figure element due to the optical proximity effect, adding identical identification data to a data group indicating an identical figure element group, estimating an influence of the optical proximity effect on the figure element group, generating correction data indicating a corrected figure element in which the influence of the optical proximity effect is compensated for at the time of exposure, creating figure data by associating data having the identical identification data with correction data having the identical identification data, and forming a mask pattern on the photomask using figure data. Thus, the computation time for correction of the layout can be reduced, thereby reducing the production time of the photomask.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a division of U.S. application Ser. No.12/481,226, filed Jun. 9, 2009, which is a division of U.S. applicationSer. No. 11/209,748, filed Aug. 24, 2005, now U.S. Pat. No. 7,562,334,which is based upon and claims the benefit of priority from the priorJapanese Patent Application No. 2005-099245, filed on 2005 Mar. 30, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing a photomask,suitable for reducing the production time, and to a method formanufacturing a semiconductor device using the photomask. Morespecifically, the present invention relates to a method formanufacturing a photomask in which data for forming a pattern on thephotomask can be created in a short time, and to a method formanufacturing a semiconductor device using the photomask.

2. Description of the Related Art

With the recent reduction in size of semiconductor devices, there hasbeen a demand for miniaturization of resist patterns formed byphotolithography for manufacturing semiconductor devices. When light isapplied to a photomask and the resist is exposed with light, a patternon the photomask is transferred to form a resist pattern. If the patternsize of the resist pattern is close to the wavelength of light used forformation of the resist pattern because miniaturization of resistpattern has advanced, the pattern on the photomask is deformed, whiletransferred, due to the optical proximity effect.

In order to prevent deformation of the resist pattern, the deformationof the resist pattern due to the optical proximity effect is predictedby simulation, etc., to correct the original pattern on the photomask.

However, such simulation, when performed using a computer, requires muchtime for computation because of the high pattern density on thephotomask. There are many approaches for reducing the computation timeto rapidly correct the pattern on the photomask, and one of them isproposed in, for example, Japanese Unexamined Patent ApplicationPublication No. 2001-13669.

In the approach proposed in this publication, regions for correction areprovided with respect to an object for correction in the input layout,and pattern-matching regions that are a certain amount larger than theregions for correction are also provided so as to surround the regionsfor correction. Then, the pattern layout in each of the pattern-matchingregions is extracted. Then, the grid in this pattern-matching region isconverted into a larger grid than the original grid. Thereafter, patternmatching is performed on a pattern region. As a result of patternmatching, for example, three kinds into which the pattern-matchingregions that are classified using the original grid are reduced to twokinds after conversion of the grid.

After pattern matching is performed on all regions for correction, theclassified pattern-matching regions are corrected. The correctedpattern-matching regions are reflected in the entirety of the inputlayout, and the corrected layout is thus obtained.

Therefore, conversion of the grid can reduce the number of kinds ofpattern-matching regions. Thus, the computation time for correcting thepattern-matching regions can also be reduced. Moreover, a correctionresult of a pattern computed for one pattern-matching region can also beused for the same kind of other pattern-matching regions, thus reducingthe computation time required for reflecting the correctedpattern-matching regions in the entirety of the input layout.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method formanufacturing a photomask in which the time for creating data forforming a pattern on the photomask is reduced to thereby reduce theproduction time of the photomask, and a method for manufacturing asemiconductor device using the photomask.

With the reduction in size of semiconductor devices, layout patterns areformed with high density on a photomask. Thus, the computation time forcorrection of the layout increases in order to compensate for aninfluence of the optical proximity effect. Therefore, a problem occursin that the time for creating data for a layout pattern on the photomaskbecomes long and the time for manufacturing the photomask alsoincreases.

Therefore, the present invention aims to provide a method formanufacturing a photomask in which the production time of the photomaskcan be reduced.

As the layout pattern density on a photomask increases, the number ofpattern matching regions also increases. Thus, the computation time forchecking the conformity of pattern matching regions by pattern matchingincreases.

Therefore, the present invention further aims to provide a method formanufacturing a photomask in which the computation time for checking theconformity is reduced, thereby reducing the production time of thephotomask.

The present invention further aims to provide a method for manufacturinga photomask in which the production time can be reduced whilemaintaining a high-accuracy layout pattern, or a high-accuracy resistpattern to be transferred to a semiconductor device, because thecomputation for correcting the layout is performed without increasingthe size of the design grid of the layout pattern on the photomask.

In one aspect of the present invention, a method for manufacturing aphotomask includes the steps of extracting data indicating a figureelement from design data, and forming a figure element group includingthis figure element and a figure element affecting the figure elementdue to the optical proximity effect. The method further includes thesteps of adding identification data to a data group indicating thefigure element group, and estimating the influence of the opticalproximity effect on the figure element group. The method furtherincludes the steps of generating correction data indicating a correctedfigure element in which the influence of the optical proximity effect iscompensated for, and configuring figure data including the correctedfigure element by associating data having identical identification datawith the correction data having the identical identification data. Themethod further includes a step of forming a mask pattern on thephotomask using the figure data.

According to the method of the present invention, identification data isassigned to data indicating a figure element group that affects a figureelement in a mask figure on a photomask due to the optical proximityeffect. Then, data indicating a corrected figure element with respect todata indicating a partial figure element is generated. When the dataindicating the corrected figure element in which the optical proximityeffect is compensated for is generated, the data indicating thecorrected figure element is distributed to data indicating other figureelements having the identical identification data. Thus, a figureelement from which the corrected figure element is to be produced caneasily be searched for and classified based on the identification dataassigned to the data indicating the figure element group, and the timefor identifying this figure element can be reduced. Moreover, even ifthere are many kinds of figure elements from which corrected figureelements are to be produced, photomask layout data can be configured ina short time based on the data indicating the corrected figure element.The production time of the photomask can therefore be reduced.

In another aspect of the present invention, there is provided anapparatus for performing the above-described method for manufacturing aphotomask.

In still another aspect of the present invention, there is provided amethod for manufacturing a semiconductor device using the photomaskmanufactured by the method described above.

According to the apparatus of the present invention, the time requiredfor manufacturing a photomask can be reduced.

According to the method for manufacturing a semiconductor deviceaccording to the present invention, with the use of a high-accuracyphotomask, a semiconductor device with high processing accuracy can beprovided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing a method for manufacturing a photomaskaccording to a first embodiment of the present invention;

FIG. 2 is a flowchart showing the details of an optical proximity effectcorrection step in the flowchart shown in FIG. 1;

FIGS. 3A and 3B are illustrations showing an initial processing step fordesign data in the flowchart shown in FIG. 2;

FIGS. 4A to 4C are illustrations showing a figure element extractingstep and an identification data assigning step in the flowchart shown inFIG. 2;

FIGS. 5A to 5C are illustrations showing a figure element group settingstep in the flowchart shown in FIG. 2;

FIGS. 6A and 6B are illustrations showing a step of assigningidentification data to a data group indicating a figure element group inthe flowchart shown in FIG. 2;

FIGS. 7A and 7B are illustrations showing an optical proximity effectestimating step and a corrected-figure generating step in the flowchartshown in FIG. 2;

FIGS. 8A and 8B are illustrations showing an inspection step for acorrected figure element generated in the flowchart shown FIG. 2;

FIG. 9 is an illustration showing a step of associating data indicatinga corrected figure element with data indicating a figure element basedon the identification data shown in FIG. 6B and distributing the dataindicating the corrected figure element to data indicating other figureelements;

FIG. 10 is an illustration showing a step of actually converting designdata that is configured to indicate the figure element into figure datafor forming a metal-film pattern on a reticle;

FIG. 11 is an illustration showing a step of forming an exposure patternon the reticle, a line width checking step, and a step of forming ametal thin-film pattern by etching in the flowchart shown in FIG. 1,which are performed using the figure data shown in FIG. 10;

FIG. 12 is a flowchart showing the details of an optical proximityeffect correction process in a method for manufacturing a photomaskaccording to a second embodiment of the present invention;

FIGS. 13A to 13C are illustrations showing a figure-element sideextracting step and an identification data assigning step in theflowchart shown in FIG. 12;

FIG. 14 is an illustration showing a figure-element side group settingstep and a step of assigning identification data to a data groupindicating a group of figure-element sides in the flowchart shown inFIG. 12;

FIG. 15 is an illustration showing an optical proximity effectestimating step and a corrected-figure generating step in the flowchartshown in FIG. 12;

FIG. 16 is an illustration of figure data that is configured bydistributing a corrected-figure-element side; and

FIG. 17 is an illustration showing a process for forming a resistpattern on a semiconductor substrate using the reticle manufactured inthe first or second embodiment, and a process for forming a metal wiringpattern on the semiconductor substrate by etching.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, second, and third embodiments of the present invention will bedescribed hereinbelow.

First Embodiment

A method for manufacturing a photomask according to a first embodimentof the present invention will be described with reference to FIGS. 1 to11. The term photomask means a sheet, typically, a quartz glass plate,having a metal thin-film pattern formed thereon. Light is applied to thephotomask to transfer the metal thin-film pattern on the photomask to aphotosensitive film, or a resist, applied to a semiconductor substrateon which a semiconductor device is formed. The materials on thesemiconductor substrate are etched using, as a mask, a resist patternformed by transferring the metal thin-film pattern on the photomask,thereby forming a circuit pattern of the semiconductor device.

FIG. 1 is a flowchart showing the method for manufacturing a photomaskaccording to the first embodiment. The method shown in FIG. 1 includesstep 1: “reticle production starts”, step 2: “create design data”, step3: “check design data”, step 4: “optical proximity effect correction”,step 5: “check optical proximity effect correction”, step 6: “formexposure pattern”, step 7: “check line width”, step 8: “form metalthin-film pattern by etching”, step 9: “modify design data”, step 10:“modify correction parameter”, step 11: “change exposure condition”, andstep 12: “reticle production ends”.

In step 1, reticle production starts. A reticle is typically, a quartzglass plate, having a metal thin-film pattern formed thereon, and is akind of photomask. Generally, a metal thin-film pattern on a reticleincludes patterned parts for circuit patterning of one chip to severalchips of a semiconductor device. The reticle is therefore used totransfer the metal thin-film pattern on the reticle to a partial regionin a semiconductor substrate on which a semiconductor device is formed.

In step 2, design data used for forming the metal thin-film pattern onthe reticle is created.

In step 3, it is determined whether or not the design data is createdaccording to a design rule. The design rule includes limitations informing the metal thin-film pattern on the reticle. The design ruleincludes, for example, limitations to ensure the minimum line width andthe minimum pattern interval of the metal thin-film pattern andlimitations to eliminate an acute-angled pattern. If the design datameets the design rule, the process proceeds to step 4. If the designdata does not meet the design rule, the process proceeds to step 9.

In step 9, the design data is corrected for a design data portion whichdoes not meet the design rule to meet the design rule.

The processing of step 4 will be schematically described although thedetails are described below with reference to FIG. 2. First, light isapplied to the reticle to produce a projected image of the metalthin-film pattern on the reticle. The projected image is passed througha lens to produce a miniature projected image. If the size of the metalthin-film pattern on the reticle is close to the wavelength of thelight, the so-called optical proximity effect prevents the miniatureprojected image from being completely similar to the metal thin-filmpattern. It is therefore necessary to deform the metal thin-film patternon the reticle and to correct the design data to form the undeformedmetal thin-film pattern so that the miniature projected image is similarto the undeformed metal thin-film pattern. In step 4, therefore, thedesign data is corrected to generate figure data for forming thedeformed metal thin-film pattern on the reticle.

In step 5, it is determined whether or not the corrected design data issuitable to produce the desired miniature projected image. If thecorrected design data is suitable, the process proceeds to step 6. Ifthe corrected design data is not suitable, the process proceeds to step10.

In step 10, the correction parameter for the called optical proximityeffect correction is modified.

In step 6, electron-beam emission from a drawing device is operatedusing the corrected design data, i.e., the figure data, to form a resistpattern on a metal thin-film.

In step 7, the line width of the resist pattern formed in step 6 ischecked. If the line width of the resist pattern is within a standardwidth, the process proceeds to step 8. If the line width of the resistpattern is not within the standard width, the process proceeds to step11.

In step 11, the exposure conditions of an electron beam from anelectron-beam exposure device, i.e., a drawing device are changed sothat the line width of the resist pattern formed in step 6 is within thestandard width. If it is determined that the line width of the resistpattern cannot be made within the standard width by changing only theexposure conditions of the electron beam, the process proceeds to step10. Then, the processing of step 4 is performed again.

In step 8, the metal thin-film is etched using the resist pattern formedin step 6 as a mask to form a metal thin-film pattern.

Therefore, the metal thin-film pattern is formed on the quartz glassplate, and, then, reticle production ends in step 12.

FIG. 2 is a flowchart showing the details of an optical proximity effectcorrection process in step 4 in the flowchart shown in FIG. 1. Theprocess shown in FIG. 2 includes step 15: “optical proximity effectcorrection starts”, step 16: “initial processing of design data”, step17: “extract figure element”, step 18: “assign identification data”,step 19: “set figure element group”, step 20: “assign identificationdata”, step 21: “estimate optical proximity effect”, step 22: “generatecorrected figure”, step 23: “inspection”, step 24: “configure figuredata by distributing figure element”, and step 25: “optical proximityeffect correction ends”.

The optical proximity effect correction process includes the processingof steps 16 to 24, and the processing of steps 16 to 24 will bedescribed with reference to FIGS. 3A to 10.

FIGS. 3A and 3B are illustrations showing the processing of step 16 inthe flowchart shown in FIG. 2.

In step 16, unnecessary data is removed from the design data, and dataindicating evaluation points is added to the design data.

FIG. 3A is an illustration showing the process of removing unnecessarydata is removed from the design data.

In FIG. 3A, as indicated in the left portion, data indicating a figureelement 32 includes data indicating four vertices 31 and data indicatingone vertex 30. The data indicating the vertex 30 does not substantiallydefine the figure, and is therefore unnecessary. The unnecessary data,i.e., the data indicating the vertex 30 that does not define the figure,is removed from the design data, i.e., the data indicating the figureelement 32, to generate data indicating the figure element 32, asindicated in the right portion in FIG. 3A. The removal of unnecessarydata from the design data has the advantage of reducing the amount ofdata to be processed.

FIG. 3B is an illustration showing the process of adding data indicatingevaluation points to the design data.

In FIG. 3B, as indicated in the left portion, data indicating a figureelement 36 includes data indicating six vertices 33, and data indicatinga figure element 37 includes data indicating four vertices 33.

In the process of adding data indicating evaluation points to the designdata, data indicating evaluation points 35 is added between the dataindicating the vertices 33 of the figure element 37 to generate dataindicating a figure element 37 including data indicating four vertices33 and four evaluation points 35, as indicated in the right portion inFIG. 3B. That is, the evaluation points 35 are added to the sides of thefigure element 37.

In the case of the figure element 36, in which the distance between thevertices 33 is long, mere addition of evaluation points does not allowfor high-accuracy estimation of the optical proximity effect later. Inthis case, in the process of adding evaluation point to the design,first, the design data indicating the figure element 36 additionallyincludes data indicating new vertices 34, and, then, data indicating theevaluation points 35 is added between the data indicating the vertices33 or between the data indicating the vertices 33 and the dataindicating the vertices 34.

By adding the evaluation points 35, the optical proximity effectcorrection can be evaluated in more detail. The sides between thevertices 33 are further divided by the vertices 34, leading tohigh-accuracy estimation.

The process of adding data indicating evaluation points to the designdata may be performed after the processing of step 20 in the flowchartshown in FIG. 2. In this case, shorter processing time and higheraccuracy can be achieved.

FIGS. 4A to 4C are illustrations showing the processing of steps 17 and18 in the flowchart shown in FIG. 2.

In step 17, data indicating one figure element is extracted from thedesign data. In step 18, identification data is generated based on thedata indicating the figure element by applying the hash function to, forexample, the relative coordinates of the vertices or the start-pointcoordinates and the relative coordinates of the vertices, and theidentification data is added to the data indicating the figure element.

The processing of steps 17 and 18 will be described hereinafter withreference to FIGS. 4A to 4C. In FIGS. 4A to 4C, the same portions areassigned the same reference numerals.

FIG. 4A shows a metal thin-film pattern on a reticle, including a set offigure elements 40 to 57. The figure elements 40 to 48 areinverse-L-shaped patterned figures each having 11 vertices, and thefigure elements 49 to 57 are rectangular patterned figures each havingfour vertices. FIG. 4A shows a grid of three rows by three columns ofpatterned figures each including a rectangular patterned figure and aninverse-L-shaped patterned figure.

FIG. 4B shows the metal thin-film pattern that has been subjected to theprocessing of steps 17 and 18, in which the figure elements 40 to 57shown in FIG. 4A are assigned identification data indicated by ID=0,ID=1, and ID=2. Specifically, the figure elements 40, 43, and 46corresponding to the inverse-L-shaped patterned figures have ID=1. Thefigure elements 41, 42, 44, 45, 47, and 48 corresponding to theinverse-L-shaped patterned figures have ID=0. The figure elements 49 to57 corresponding to the rectangular patterned figures have ID=2.

FIG. 4C is an illustration showing the process of extracting dataindicating one figure element from the design data, and the process ofapplying the hash function to the data indicating the figure element togenerate identification data and adding the identification data to thedata indicating the figure element.

First, design data 58 includes a set of vertex coordinate data of afigure element, which are indicated by “X0: the start point X”, “Y0: thestart point Y”, “X1: the first point X”, “Y1: the first point Y”, “X2:the second point X”, “Y2: the second point Y”, “X3: the third point X”,“Y3: the third point Y”, “X4: the fourth point X”, “Y4: the forth pointY”, “X5: the fifth point X”, “Y5: the fifth point Y”, “X6: the sixthpoint X”, “Y6: the sixth point Y”, “X7: the seventh point X”, “Y7: theseventh point Y”, “X8: the eighth point X”, “Y8: the eighth point Y”,“X9: the ninth point X”, “Y9: the ninth point Y”, “X10: the tenth pointX”, and “Y10: the tenth point Y”.

In the process of extracting data indicating one figure element from thedesign data, first, vertex coordinate data associated with a figureelement 59 having the start point and the first to tenth points asvertices is extracted from the design data 58, and is configured as aset of data. Then, the uppermost leftmost vertex is defined as the startpoint (X0, Y0), and the relative coordinates (DX1, DY1, DX2, DY2, DX3,DY3, DX4, DY4, DX5, DY5, DX6, DY6, DX7, DY7, DX8, DY8, DX9, DY9, DX10,and DY10) from the start-point vertex of the figure element 59 aredetermined from the vertex data belonging to the set of data, and data60 indicating the figure element 59 collectively including thestart-point data and the relative coordinates of the vertices iscreated.

In the process of applying the hash function to the data indicating thefigure element to generate identification data and adding theidentification data to the data indicating the figure element, first,identification data is generated based on the data 60 by, for example,applying the hash function to the relative coordinates of the verticesof the figure element 59. The identification data generated by the hashfunction even based on different figure elements may be the same. Thus,figure elements having the identical identification data are compared,and are further assigned different identification data. Althoughidentification data indicated by a number, such as ID=0, ID=1, and ID=2,are shown in FIG. 4B, data indicating a symbol, etc., may be used asidentification data. The hash function is a function which convertsgiven original text, original numbers, or original coordinates into acharacter or number string having a fixed length in order to acquire akey allowing for high-speed search using the hash method. Then, theidentification data is assigned to the data 60 to produce data 61indicating the figure element 59 assigned with the identification data.It is to be understood that the data 60 indicating the same figureelement is assigned the identical identification data.

FIGS. 5A to 5C are illustrations showing the processing of step 19 inthe flowchart shown in FIG. 2.

The processing of step 19 includes a process of setting a figure regionbased on a figure element to be corrected, and a process of extracting afigure element group overlapping or adjacent to the figure region. Inthe process of setting a figure region based on a figure element to becorrected, a figure outer frame is defined with respect to a figureelement, and the figure outer frame is enlarged to configure a figureregion. In the process of extracting a figure element group overlappingor adjacent to the figure region, a figure element group overlapping oradjacent to the figure region is identified based on the identificationdata assigned to data indicating the figure element, and a data groupindicating the figure element group is extracted.

The process of setting a figure region based on a figure element to becorrected will be described with reference to FIGS. 5A and 5B, and theprocess of extracting a figure element group overlapping or adjacent tothe figure region will be described with reference to FIG. 5C. In FIGS.5A to 5C, the same portions are assigned the same reference numerals.

FIG. 5A shows a figure outer frame 66 based on a figure element 65 to becorrected, which is used in the process of setting a figure region basedon a figure element to be corrected. One point defining the figure outerframe 66 is the maximum point expressed by the X coordinate having themaximum value and the Y coordinate having the maximum value in the X andY coordinates of vertices of the figure element 65 to be corrected. Theother point defining the figure outer frame 66 is the minimum pointexpressed by the X coordinate having the minimum value and the Ycoordinate having the minimum value in the X and Y coordinates of thevertices of the figure element 65.

FIG. 5B shows a figure region 67 that is formed by enlarging the figureouter frame 66 by a certain factor. The enlargement factor is determinedso that the figure region 67 is equal to a region that is determined tobe necessary for estimating the influence of the optical proximityeffect on the figure outer frame 66 of the designated figure element 65.Thus, the enlargement factor depends upon the conditions, such as thesize of the figure element 65 and the optical wavelength used forradiation. Since the influence of the optical proximity effect isestimated by simulation using a computer, the enlargement factor variesdepending upon the performance of the computer used for the numericalcalculation. While the figure region 67 is formed by enlarging thefigure outer frame 66 by a certain factor, the figure region 67 may beformed by enlarging the figure outer frame 66 by a certain width.

FIG. 5C is an illustration showing the process of identifying a figureelement group overlapping or adjacent to the figure region 67 based onthe identification data assigned to the data indicating the figureelement 65 and extracting a data group indicating the figure elementgroup. First, in the process of identifying a figure element groupoverlapping or adjacent to the figure region 67 based on theidentification data assigned to the data indicating the figure element65, figure elements 69 and 70 which at least partially overlap or are atleast partially included in the figure region 67 shown in FIG. 5C areidentified from other figure elements 68 based on identification dataassigned to data indicating the figure elements 69 and 70. In theprocess of identifying a figure element group overlapping or adjacent tothe figure region 67 based on the identification data assigned to thedata indicating the figure element 65, a figure element 71 adjacent tothe figure region 67 is also identified from the other figure elements68 based on identification data assigned to data indicating the figureelement 71. Thereafter, in the process of extracting a data groupindicating the figure element group, the extracted figure elements 69,70, and 71 are combined into a figure element group, and a data groupindicating the figure element group is created.

FIGS. 6A and 6B are illustrations showing the process of assigningidentification data to the data indicating the figure element group(step 20 in the flowchart shown in FIG. 2).

In the process of assigning identification data to the data groupindicating the figure element group, the absolute coordinates ofvertices of figure elements, which are included in an identificationdata group assigned to the data group indicating the figure elementgroup and the data indicating the figure element, are converted into therelative coordinates from the coordinates of the vertices of thedesignated figure element, and the hash function is applied to theconverted relative coordinates to generate identification data. Thegenerated identification data is assigned to the data group indicatingthe figure element group.

In FIGS. 6A and 6B, the same portions are assigned the same referencenumerals.

FIG. 6A shows an identification data group 95 assigned to a data groupindicating a figure element group including the absolute coordinateswith respect to a designated figure element 79 and data indicating thefigure element 79. In FIG. 6A, figure elements 75 to 78 and 80 to 92 areadjacent to the figure element 79, and a figure region 93 is definedwith respect to the figure element 79.

In FIG. 6A, the identification data group 95 includes “ID:identification data of the figure element 79”, “(MXp0, MYp0): theabsolute coordinates of the figure element 87”, “ID0: identificationdata of the figure element 87”, “(MXp1, MYp1): the absolute coordinatesof the figure element 88”, “ID1: identification data of the figureelement 88”, “(MXp2, MYp2): the absolute coordinates of the figureelement 76”, “ID2: identification data of the figure element 76”,“(MXp3, MYp3): the absolute coordinates of the figure element 82”, and“ID3: identification data of the figure element 82”.

For example, the description “(MXp0, MYp0): the absolute coordinates ofthe figure element 87” means that the start-point vertex of the figureelement 87 is expressed by the absolute coordinates and the coordinatesof the other vertices are expressed by the relative coordinates from thestart-point vertex. The same applies to “(MXp1, MYp1): the absolutecoordinates of the figure element 88”, “(MXp2, MYp2): the absolutecoordinates of the figure element 76”, and “(MXp3, MYp3): the absolutecoordinates of the figure element 82”.

The description “ID: identification data of the figure element 79” meansidentification data that is generated by applying the hash function tothe data indicating the figure element 79 and that is assigned to thedata indicating the figure element 79. The same applies to “ID0:identification data of the figure element 87”, “ID1: identification dataof the figure element 88”, “ID2: identification data of the figureelement 76”, and “ID3: identification data of the figure element 82”.

FIG. 6B is an illustration showing the process of assigningidentification data to the data group indicating the figure elementgroup (step 20 in the flowchart shown in FIG. 2). In FIG. 6B, the figureregion 93, indicated by a dotted line, is defined with respect to thedesignated figure element 79. FIG. 6B shows that the figure elements 87,88, 76, and 82 are extracted. FIG. 6B also shows that the figureelements 75, 77, 78, 80, 81, 83, 84, 85, 86, 89, 90, 91, and 92 areadjacent to the figure element 79.

In the process of assigning identification data to the data groupindicating the figure element group, first, the vertex coordinates ofthe figure elements 87, 88, 76, and 82 in the identification data group95 are converted from the absolute coordinates to the relativecoordinates from the vertex coordinates of the designated figure element79.

Specifically, the relative coordinates are determined by subtracting thevalues of the coordinates of the start-point vertex of the figureelement 79 from the values of the coordinates of the start-pointvertices of the figure elements 87, 88, 76, and 82. Then, thecoordinates of the other vertices of the figure elements, which areexpressed by the relative coordinates from the coordinates of thestart-point vertices of the figure elements 87, 88, 76, and 82, areadded to configure a data table 96. The data table 96 includes dataindicating the figure elements 87, 88, 76, and 82 including the relativecoordinates, and identification data assigned to the data indicating thefigure elements 79, 87, 88, 76, and 82. In FIG. 6B, the data indicatingthe figure elements 87, 88, 76, and 82 including the relativecoordinates includes “ID: identification data of the figure element 79”,“(Xp0, Yp0): the relative coordinates of the figure element 87 ((thestart-point coordinates of the figure element 87)—(the start-pointcoordinates of the Figure element 79))”, “ID0: identification data ofthe figure element 87”, “(Xp1, Yp1): the relative coordinates of thefigure element 88 ((the start-point coordinates of the figure element88)—(the start-point coordinates of the figure element 79))”, “ID1:identification data of the figure element 88”, “(Xp2, Yp2): the relativecoordinates of the figure element 76 ((the start-point coordinates ofthe figure element 76)—(the start-point coordinates of the figureelement 79))”, “ID2: identification data of the figure element 76”,“(XpP3, Yp3): the relative coordinates of the figure element 82 ((thestart-point coordinates of the figure element 82)—(the start-pointcoordinates of the figure element 79))”, and “ID3: identification dataof the figure element 82”.

Then, identification data F(ID, Xp0, Yp0, ID0, Xp1, Yp1, ID1, Xp2, Yp2,ID2, Xp3, Yp3, ID3) including a character or number string having afixed length is generated. This identification data is generated byapplying the hash function using the description “ID: identificationdata of the figure element 79”, “(Xp0, Yp0): the relative coordinates ofthe figure element 87 ((the start-point coordinates of the figureelement 87)—(the start-point coordinates of the figure element 79))”,“ID0: identification data of the figure element 87”, “(Xp1, Yp1): therelative coordinates of the figure element 88 ((the start-pointcoordinates of the figure element 88)—(the start-point coordinates ofthe figure element 79))”, “ID1: identification data of the figureelement 88”, “(Xp2, Yp2): the relative coordinates of the figure element76 ((the start-point coordinates of the figure element 76)—(thestart-point coordinates of the figure element 79))”, “ID2:identification data of the figure element 76”, “(XpP3, Yp3): therelative coordinates of the figure element 82 ((the start-pointcoordinates of the figure element 82)—(the start-point coordinates ofthe figure element 79))”, and “ID3: identification data of the figureelement 82”. The identification data generated by the hash function evenbased on different figure element groups may be the same. Thus, figureelement groups having the identical identification data are compared,and are further assigned different identification data. The data table96 including data indicating a figure element group including therelative coordinates and identification data is thus created. Althoughidentification data indicated by a number, such as ID=0, ID=1, ID=2,ID=3, ID=4, ID=5, and ID=6, are shown in FIG. 6B, data indicating asymbol, etc., may be used as identification data.

FIGS. 7A and 7B are illustrations showing the processing of steps 21 and22 in the flowchart shown in FIG. 2.

In step 21, the influence of the optical proximity effect on the shapeof a projected image produced by applying light to a figure element isestimated by computer-based simulation. In step 22, a corrected figureelement in which the shape of the figure element is corrected so thatthe shape of the projected image becomes similar to the shape of thefigure element is generated.

In FIGS. 7A and 7B, the same portions are assigned the same referencenumerals.

FIG. 7A is an illustration showing the process of estimating theinfluence of the optical proximity effect on the shape of a projectedimage produced by applying light to a figure element by computer-basedsimulation. In FIG. 7A, figure elements 102, 103, and 104 are extractedin a figure region 100 defined with respect to a designated figureelement 101. A projected image 105 of the designated figure element 101is predicted by computer-based simulation.

In the process of estimating the influence of the optical proximityeffect, the projected image 105 of the designated figure element 101 isdetermined by computer-based simulation. The projected image 105 is aprojected image produced by applying light to the designated figureelement 101, taking the optical proximity effect into consideration. Ingeneral, the vertex portions of the projected image 105 arequadrant-shaped but not right-angled due to the effect of the opticalproximity effect. The sides of the projected image 105 are generallyinside the sides of the designated figure element 101. Moreover, forexample, a portion of the designated figure element 101 which isadjacent to the figure element 103 is strongly affected by the opticalproximity effect resulting from the figure element 103, and is thereforeshaped into concave.

Then, the shape of the designated figure element 101 is compared withthe projected image 105 to estimate the influence of the opticalproximity effect.

FIG. 7B is an illustration showing the process of generating a correctedfigure element in which the shape of the figure element is corrected sothat the shape of the projected image becomes similar to the shape ofthe figure element. FIG. 7B shows the designated figure element 101, thefigure region 100, and the extracted figure elements 102, 103, and 104.FIG. 7B also shows a corrected figure element 106 produced by performinga corrected-figure generation process on the designated figure element101. In FIG. 7B, a projected image 107 is predicted with respect to thecorrected figure element 106 by computer-based simulation.

In the process of generating a corrected figure element in which theshape of the figure element is corrected so that the shape of theprojected image becomes similar to the shape of the figure element, theshape of the projected image 107 produced by computer-based simulationis compared with the shape of the designated figure element 101. Then,the designated figure element 101 is corrected so that the shape of theprojected image 107 becomes similar to the designated figure element101, and the corrected figure element 106 is generated. For example,correction is performed so that the corrected figure element 106additionally includes small rectangular figures at the vertex portionsthereof in order to prevent the vertex portions of the projected image107 from being shaped into quadrant. Correction is further performed sothat the sides of the corrected figure element 106 become outside thesides of the designated figure element 101. The shape of the projectedimage 107 of the corrected figure element 106 is therefore similar tothe shape of the designated figure element 101.

The processing of steps 21 and 22 is performed on one of the figureelements having the identical identification data shown in FIG. 4C in afigure element group having the identical identification data shown inFIG. 6B when this figure element group resides in the figure region 100.

That is, when figure elements of the metal thin-film pattern on thephotomask are classified using the identification data shown in FIG. 6Band the identification data shown in FIG. 4C, a figure element that isdetermined to be unique is corrected, and a corrected figure isgenerated.

In this classification of figure elements, generally, a long time isrequired for searching or sorting if data indicating the figure elementsincludes only coordinate data. In the first embodiment, however,identification data is generated based on the hash function, and thetime for searching or sorting can therefore be reduced.

FIGS. 8A and 8B are illustrations showing the process of inspecting thecorrected figure element (step 23 in the flowchart shown in FIG. 2).

In the processing of step 23, evaluation points of a figure element arecompared with evaluation points of a projected image of the figureelement to inspect deformation of the projected image due to the opticalproximity effect, and the consistency in shape between the projectedimage and the figure element is checked.

FIG. 8A shows that a figure element 111 and a projected image 110 of thefigure element 111 are compared at evaluation points 113 to inspectdeformation of the projected image 110 due to the optical proximityeffect. In FIG. 8A, the figure element 111 having vertices 112 isindicated by a dotted line, and the vertices 112 are indicated by largedotted circles. The evaluation points 113 are indicated by small dottedcircles. The projected image 110 shown in FIG. 8A is indicated by asolid line.

In FIG. 8A, the figure element 111 and the projected image 110 of thefigure element 111 are compared at the evaluation points 113, asindicated by black arrows, thereby inspecting deformation of theprojected image 110 due to the optical proximity effect. This inspectionis performed using data indicating the figure element 111, data of theevaluation points 113 included in the data indicating the figure element111, and data indicating the projected image 110. While the figureelement 111 and the projected image 110 of the figure element 111 arecompared at the evaluation points 113 in FIG. 8A, the comparison may beperformed at the vertices 112 and a comparison result may be used in theinspection process. In this case, the allowable error increases when avertex is at the corner. The accuracy of the inspection can be enhancedby using a combination of the comparison at the vertices 112 between thefigure element 111 and the projected image 110 and the comparison at theevaluation points 113 on the sides of the figure element 111 and theprojected image 110.

FIG. 8B shows that the figure element 111 and a projected image 114 of acorrected figure element generated by simulation are compared at theevaluation points 113 to determine the consistency in shape between theprojected image 114 and the figure element 111.

In FIG. 8B, a dotted line, large dotted circles, and small dottedcircles indicate similar portions to those shown in FIG. 8A. In FIG. 8B,a solid line indicates the projected image 114.

In FIG. 8B, the figure element 111 and the projected image 114 of thecorrected figure element are compared at the evaluation points 113, asindicated by black arrows. Also, the inspection described above isperformed by computer-based simulation using data indicating the objectto be inspected. While the figure element 111 and the projected image114 of the corrected figure element are compared at the evaluationpoints 113 in FIG. 8B, the comparison may be performed at the vertices112 and a comparison result may be used in the inspection process. Inthis case, the allowable error increases when a vertex is at the corner.Then, it is determined (in step 23 in the flowchart shown in FIG. 2)whether or not the difference in shape between the projected image 114of the corrected figure element and the figure element 111 is within apredetermined range as a result of the inspection. If the difference iswithin the predetermined range, this corrected figure element is used asthe desired corrected figure element. If the difference in shape betweenthe projected image 114 of the corrected figure element and the figureelement 111 is not within the predetermined range, the process returnsto step 19 in the flowchart shown in FIG. 2, and another correctedfigure element is produced.

The processing of step 24 in the flowchart shown in FIG. 2 will bedescribed with reference to FIGS. 9 and 10. In step 24, data indicatingthe corrected figure element and data indicating the figure element areassociated based on the identification data shown in FIG. 6B. The dataindicating the corrected figure element is further distributed to dataindicating other figure elements having the identical identificationdata, thereby actually converting design data that is configured toindicate the figure element into figure data for forming the metal filmpattern on the photomask.

FIG. 9 is an illustration showing the process of associating dataindicating a corrected figure element with data indicating a figureelement based on the identification data shown in FIG. 6B anddistributing the data indicating the corrected figure element to dataindicating other figure elements. FIG. 9 shows an originaltwo-row-by-three-column FIG. 119, and a two-row-by-three-column FIG. 120after performing distribution. A two-row-by-three-column figure is agrid of two rows by three columns of arbitrary figure elements in an nrow by m column figure group having a plurality of figure elements,where n and m are natural numbers more than four, and excludesperipheral columns or peripheral rows.

In the process of associating data indicating a corrected figure elementwith data indicating a figure element based on the identification datashown in FIG. 6B, therefore, in the original two-row-by-three-columnFIG. 119 shown in FIG. 9, figure elements 116 in which a figure elementgroup having certain identification data, e.g., ID=0, resides in afigure region 115 are replaced with a hatched corrected figure element118.

In the process of distributing the data indicating the corrected figureelement to data indicating other figure elements having the identicalidentification data, in the original two-row-by-three-column FIG. 119shown in FIG. 9, the figure elements 116 in which a figure element grouphaving the identical identification data, e.g., ID=0, resides in thefigure region 115 are replaced with the same corrected figure element118, and the two-row-by-three-column FIG. 120 shown in FIG. 9 is thuscreated.

For convenience of illustration, in the foregoing description,distribution of a figure element is performed using figure elements. Afigure element is distributed by a computer, and this processing maytherefore be performed using indicating the figure elements 116 and 117,the corrected figure element 118, etc.

FIG. 10 is an illustration showing the process of actually convertingdesign data that is configured to indicate the figure element intofigure data for forming the metal-film pattern on the reticle.

In FIG. 10, figure data 128 includes a figure element 121 having afigure element group assigned with identification data ID=6, correctedfigure elements 122 having a figure element group assigned withidentification data ID=2, corrected figure elements 123 having a figureelement group assigned with identification data ID=5, a corrected figureelement 124 having a figure element group assigned with identificationdata ID=1, corrected figure elements 125 having a figure element groupassigned with identification data ID=0, a corrected figure element 126having a figure element group assigned with identification data ID=3,and figure elements 127 having a corrected figure element group assignedwith identification data ID=4.

In the process of actually converting design data that is configured toindicate the figure element into figure data for forming the metal filmpattern on the reticle, the process of associating data indicating acorrected figure element with data indicating a figure element based onthe identification data shown in FIG. 6B and distributing the dataindicating the corrected figure element to data indicating other figureelements is performed on all figure elements.

As shown in FIG. 10, the figure data 128 indicating the metal filmfigures on the reticle includes data indicating the corrected figureelements 121 to 127.

The more details of the association process based on the identificationdata shown in FIG. 6B will be described. First, data indicating acorrected figure element includes the origin coordinates indicating thestart point, and the relative coordinates of the other vertices from thestart point. Therefore, the data indicating the corrected figure elementdoes not have the absolute coordinates. On the other hand, dataindicating a figure element which the data indicating the correctedfigure element is based on has the absolute coordinates; this dataincludes the absolute coordinates indicating the start point and therelative coordinates indicating the other vertices from the start point.

The absolute coordinates of the data indicating the figure element andidentification data of a figure element group included in a figureregion that is defined to correct for the shape of the figure elementare extracted from data indicating the figure element group. Thereafter,the data indicating the corrected figure element and the absolutecoordinates are associated based on the identification data. Thisoperation corresponds to the association process based on theidentification data shown in FIG. 6B.

FIG. 11 is a diagram showing the process of forming an exposure patternon a reticle, checking the line width, and forming a metal thin-filmpattern by etching (steps 6 to 8 in the flowchart shown in FIG. 1) usingthe figure data 128 shown in FIG. 10.

In FIG. 11, a figure drawing device includes a control unit 130 and abeam emission unit 131.

The beam emission unit 131 of the figure drawing device includes a beamemitter 138, an electrostatic lens 139 focusing a beam, a beam-blank 140having the function of blocking the beam, a deflector 141 controllingthe direction of the beam, an electrostatic lens 142 focusing the beamonto an object to be irradiated with the beam, and a stage 144 having aphotomask (or reticle) 143, e.g., a reticle, mounted thereon. Thecontrol unit 130 of the graphic drawing device functions to control thebeam emission unit 131 and to control emission of a beam based on figuredata 145 stored therein. The control unit 130 includes a beam controller132 controlling the beam emitter 138, a lens controller 133 controllingthe electrostatic lenses 139 and 142, a beam-blank controller 134controlling the beam blank 140, a deflector controller 135 controllingthe deflector 141, a stage controller 137 controlling the stage 144, anda controller 136. The controller 136 controls the beam controller 132,the lens controller 133, the beam-blank controller 134, the deflectorcontroller 135, and the stage controller 137 based on the figure data145.

The processing of step 6 in the flowchart shown in FIG. 1, in which anexposure pattern is formed on the reticle 143, is performed according tothe following procedure. First, a metal thin-film 147 is deposited on aquartz plate 146, and is then coated with a resist 148. Then, the beamemitter 131 emits a beam to the resist 148 using the figure data 128shown in FIG. 10 so as to form a desired resist pattern. Layers 150after beam irradiation are shown in cross-section. Then, the resist 148is removed while a resist portion 149 that is cured by beam radiation isleft, thereby forming a resist pattern. Layers 151 with the resist 148being removed are shown in cross-section.

The process of checking the line width (step 7 in the flowchart shown inFIG. 1) is then performed on the resist pattern. If the line width ofthe resist pattern is equal to a predetermined line width, the processproceeds to step 8 in the flowchart shown in FIG. 1.

The process of forming a metal thin-film pattern by etching (step 8 inthe flowchart shown in FIG. 1) is performed according to the followingprocedure. First, the metal thin-film 147 is patterned by anisotropicetching using the resist pattern as a mask. Then, layers 152 with themetal thin-film 147 being etched are shown in cross-section. Then, theresist pattern is removed, thereby obtaining layers 153 in cross-sectionwith the resist pattern being removed. The patterned metal thin-film 147is left on the quartz plate 146, thereby forming a metal thin-filmpattern on the reticle.

The method for manufacturing a reticle according to the first embodimentincludes the steps of creating design data of a metal thin-film patternon a reticle, checking the design data, generating figure data forforming a corrected metal thin-film pattern on the reticle by performingoptical proximity effect correction, checking the optical proximityeffect, forming an exposure pattern, checking the line width of theexposure pattern, i.e., the resist pattern, and forming a metalthin-film pattern by etching. The step of generating figure data forforming a metal thin-film pattern by performing optical proximity effectcorrection includes the steps of performing initial processing on designdata, extracting a figure element, assigning identification data,setting a figure element group, assigning identification data,estimating the optical proximity effect, generating a corrected figure,performing inspection, and configuring figure data by distributing acorrected figure element.

According to the method for manufacturing a reticle according to thefirst embodiment, therefore, the time required for manufacturing thereticle can be reduced. This is because the time for generating figuredata for a metal thin-film pattern on the reticle is reduced.

The time for generating the figure data is reduced because all figureelements are not subjected to the corrected-figure generation process,but only one of the figure elements having the identical identificationdata shown in FIG. 4C in which a figure element group having theidentical identification data shown in FIG. 6B is included in a figureregion is subjected to the corrected-figure generation process. Althoughthe time for assigning identification data and for checking theconformity between the identification data is required, the process ofgenerating identification data and checking the conformity between theidentification data can be rapidly performed because the identificationdata is generated using the hash function. Therefore, the time forassigning identification data and checking the conformity between theidentification data can greatly be reduced.

According to the method for manufacturing a reticle according to thefirst embodiment, furthermore, the time for manufacturing a reticle canbe reduced even if a smaller grid is used as the grid of the figuredata. According to the method for manufacturing a reticle according tothe first embodiment, therefore, a reticle having a high-accuracypattern can also be manufactured.

Second Embodiment

A method for manufacturing a photomask according to a second embodimentof the present invention has manufacturing processes similar to those inthe method for manufacturing a photomask according to the firstembodiment, except for optical proximity effect correction (step 4 inthe flowchart shown in FIG. 1). An optical proximity effect correctionprocess in the method for manufacturing a photomask according to thesecond embodiment will be described hereinbelow with reference to FIGS.12 to 16.

FIG. 12 is a flowchart showing the details of the optical proximityeffect correction process in the method for manufacturing a photomaskaccording to the second embodiment. The process shown in FIG. 12includes step 155: “optical proximity effect correction starts”, step156: “initial processing of design data”, step 157: “extractfigure-element sides”, step 158: “assign identification data”, step 159:“set group of figure-element sides”, step 160: “assign identificationdata”, step 161: “estimate optical proximity effect”, step 162:“generate corrected figure”, step 163: “inspection”, step 164:“configure figure data by distributing of corrected-figure-elementside”, and step 165: “optical proximity effect correction ends”.

The optical proximity effect correction process shown in FIG. 12includes the processing of steps 156 to 164, and the processing of steps156 to 164 will be described with reference to FIGS. 13 to 16.

FIGS. 13A to 13C are illustrations showing the processing of steps 157and 158 in the flowchart shown in FIG. 12.

In step 157, data indicating sides of a figure element constitutingdesign data is extracted. In step 158, identification data is generatedbased on the data indicating the sides of the figure element, e.g., byapplying the hash function to side data 174 indicating the sides of thefigure element and additional information 175, and the identificationdata is added to the data indicating the sides of the figure element.

In FIGS. 13A to 13C, the same portions are assigned the same referencenumerals. The processing of steps 157 and 158 in the flowchart shown inFIG. 12 will now be described with reference to FIGS. 13A to 13C.

FIG. 13A shows an exemplary metal thin-film pattern on a reticle,showing a figure element section 170. The figure element section 170includes five figure elements.

FIG. 13B shows a figure-element side section 171. The figure elements inthe figure element section 170 are divided based on figure-elementvertices 173. The figure-element side section 171 includes a pluralityof figure-element sides 172.

FIG. 13C is an illustration showing the process of extracting dataindicating sides of a figure element constituting design data, and theprocess of generating identification data by applying the hash functionbased on the data indicating the sides of the figure element and addingthe identification data to the data indicating the sides of the figureelement.

The figure-element side section 171 is indicated by a plurality ofvertex data sets. In the process of extracting data indicating sides ofa figure element constituting design data, first, vertex data setsdefining sides of each figure element are extracted. Then, one vertexdata set is used as start-point data (expressed by S(x1, y1) in FIG.13C), and the other vertex data set is used as end-point data (expressedby E(x2, y2) in FIG. 13C) so that the left side becomes the inside ofthe figure. Thus, vector data having the start point and the end pointas elements, i.e., data including S(x1, y1) and E(x2, y2), is extractedas figure-element side data 174. Additional information data 175 isadded to the vector data. The additional information data 175 mayinclude, for example, “a: the figure type to which the side belongs”,“b: the amount of correction for the side”, “c: a flag indicatingwhether or not the side is to be corrected”, “d: the inclusionrelationship (indicating whether or not this figure is inside anotherfigure)”, “e: a flag indicating the occurrence of an error during theprocess”, and “f: other data”.

Next, in the process of generating identification data by applying thehash function to the data indicating the sides of the figure element andadding the identification data to the data indicating the sides of thefigure element, first, the hash function is applied to a side-directionvalue (indicated by the relative coordinates of the end-pointcoordinates with respect to the start-point coordinates) computed fromthe figure-element side data 174 and to the additional information data175 to generate identification data 176. The identification data 176 isdata including a symbol, a number, etc. The hash function is a functionwhich converts given original text, original numbers, or originalcoordinates into a character or number string having a fixed length inorder to acquire a key allowing for high-speed search using the hashmethod. Then, the identification data 176 is assigned to thefigure-element side data 174 and the additional information 175 toproduce the figure-element side data 174 and the additional information175 added with the identification data 176. The figure-element side data174 and the additional information 175 that indicate different contentare assigned different identification data 176. If the identicalidentification data is found, input data sets of the hash function arecompared, and different input content is assigned differentidentification data. It is to be understood that the identicalidentification data 176 is assigned to the figure-element side data 174and the additional information 175 that indicate the same content.

FIG. 14 is an illustration showing the process of setting a group offigure-element sides and assigning identification data to a data groupindicating the group of figure-element sides (steps 159 and 160 in theflowchart shown in FIG. 12).

The processing of step 159 in the flowchart shown in FIG. 12 includes astep of setting a figure region based on a figure-element side to becorrected, and a step of extracting a figure-element side groupoverlapping or adjacent to the figure region. In the step of setting afigure region based on a figure-element side to be corrected, a regionaffected by the optical proximity effect is set as a figure region. Inthe step of extracting a figure-element side group overlapping oradjacent to the figure region, a group of figure-element sides thatoverlaps or is adjacent to the figure region is identified based on theidentification data assigned to the figure-element side data, and a datagroup indicating the group of figure-element sides is extracted.

In the processing of step 160 in the flowchart shown in FIG. 12,correction information data is assigned to the data group indicating thegroup of figure-element sides, and the hash function is applied to thecorrection information data and the data group indicating the group offigure-element sides to generate identification data. The identificationdata is then assigned to the data group indicating the group offigure-element sides. In the processing of step 160, by retrieving theidentification data, identification data distinguished from otheridentification data, i.e., unique identification data, is identified.The hash function includes, for example, a function which determines thesum of X coordinates of the data group indicating the group offigure-element sides.

Referring to FIG. 14, in the processing of step 159, first, afigure-element side 182 to be corrected is selected from a group 180 offigure-element sides. One evaluation point (reference point) is definedon the side 182. Then, as indicated in an enlarged portion 181, a regionin which the figure-element side 182 to be corrected is affected by theoptical proximity effect is set as a figure region 190. Then, a group offigure-element sides overlapping or adjacent to the figure region 190 isextracted from other figure-elements sides 185. Then, a data group 186indicating a group 183 of figure-element sides with respect to thefigure-element side 182 to be corrected is created. The data group 186must define a closed figure when data indicating the figure-element side182 to be corrected is corrected taking the optical proximity effectinto consideration. Thus, the data group 186 includes data indicatingimaginary sides 184 indicated in the enlarged portion 181. Theindicating imaginary sides 184 are necessary for computation to estimatecorrection that is performed on the figure-element side 182 to becorrected. The data group 186 collectively includes the data (174, 175,and 176 in FIG. 13C) indicating figure-element sides around the side182, including the imaginary sides 184 and the side 182. In thisinformation, the vertex coordinates 174 shown in FIG. 13C have beenconverted into the relative coordinates with respect to the evaluationpoint (reference point).

In the processing of step 160, first, correction information 187 isgenerated for the data group 186 indicating the group 183 offigure-element sides with respect to the figure-element side 182 to becorrected. The correction information 187 includes “a: the inclusionrelationship of the evaluation point”, “b: side information on the sidesaround the evaluation point”, and “c: other information”. Then, the hashfunction is applied to data indicating the correction information 187and the data group 186 to generate identification data 188, and theidentification data 188 is assigned to the data group 186. All sides tobe corrected within the group 180 shown in FIG. 14 also are subjected tothis process, and are assigned the identification data 188.

Then, sides having the identification data 188 are compared and sortedto classify the identification data 188. It ensures that sides havingdifferent identification data 188 have different information (187 and186); however, sides having the identical identification data 188 do notnecessarily have the identical information (187 and 186). The sides tobe corrected having the identical identification data 188 are comparedin detailed information (187 and 186). If the sides have differentinformation (187 and 186), different identification data 188 areassigned to these sides.

Thus, the sides having the identical identification data 188 have thesame amount of correction. One of the sides having the identicalidentification data 188 is selected as a representative, and therepresentative side is set as a side 189 of a figure element for whichestimation of the amount of correction is necessary. The representativeside 189 may be arbitrarily selected, and either representative sideresults in the same estimated amount of correction. Preferably, forexample, the side having the start point having the minimum values inthe absolute coordinate system is set as the representative.

In the foregoing description, classification of the uniqueidentification data 188 is performed by searching using simplecomparison and sorting. The classification of the unique identificationdata 188 may also be performed while considering rotation offigure-element sides, upside-down sides of figure elements, removal of aportion of a side group for a figure set as sides of figure elementswhich may not affect the correction, and further division of thefigure-element sides.

FIG. 15 is an illustration showing the process of estimating the opticalproximity effect and generating a corrected figure (steps 161 and 162 inthe flowchart shown in FIG. 12).

In step 161, the influence of the proximity effect on the shape of aprojected image generated by applying light to a figure element isestimated by computer-based simulation. In step 162, a corrected figureelement in which the figure element is corrected for the shape so thatthe shape of the projected image becomes similar to the shape of thefigure element is generated.

Referring to FIG. 15, in the processing of step 161, first, a projectedimage of a figure element group 191 is determined by computer-basedsimulation. That is, as indicated in an enlarged portion 192 showing aportion of the figure element group 191, a projected image 196 isproduced by applying light to a portion of a figure element. Then, aside 195 of the figure element and a side portion of the projected image196 are compared in shape to estimate the influence of the opticalproximity effect.

Then, the processing of step 162 is performed by the followingprocedure: first, as indicated in an enlarged portion 194 showing aportion of a corrected figure element 193, a corrected-figure-elementside 197 in which a side portion of a projected image 198 of the portionof the corrected figure element 193 is similar to the side 195 of thefigure element is generated, taking an influence of the opticalproximity effect into consideration. The processing of step 162 isperformed only on the side (the side 189 shown in FIG. 14) of the figureelement for which it is determined in step 159 that estimation of thecorrection is necessary. The distance between the side 195 of the figureelement and the corrected-figure-element side 197 corresponds to theamount of correction. The amount of correction is determined for eachside, and is then stored as the amount of correction (included in “c:other information” in the correction information 187 shown in FIG. 14)corresponding to the identification data (188 in FIG. 14).

FIG. 16 shows figure data 200 that is created by performing theprocessing of step 164 in the flowchart shown in FIG. 12. The figuredata 200 includes a set of corrected figure elements 201.

The processing of step 164 is performed by the following procedure:first, since the amount of correction corresponding to all uniqueidentification data 188 has been determined, the amount of correctionfor figure-element sides having the identical identification data 188 isdetermined accordingly. After the amount of correction for allfigure-element sides is determined, the figure is deformed according tothe amount of correction for each of the sides. If it is determined instep 163 in the flowchart shown in FIG. 12 that the amount of correctionis not sufficient, the amount of additional correction is determined. Inthis case, the deformed figure-element sides are returned to the initialstate, and, instead, the amount of correction for a figure-element side(“b: the amount of correction for the side” in the additionalinformation 175 shown in FIG. 13C) is stored. The subsequent estimationof the amount of correction is performed considering “b: the amount ofcorrection for the side” in the additional information 175 shown in FIG.13C. Therefore, the set of correction figure elements 201 is produced.In this way, data indicating all figure-element sides is deformed usingthe amount of correction based on the identification data, therebyconverting the design data constituted by figure-element side data intofigure data to be actually used to form a metal thin-film pattern on aphotomask.

Association based on the identification data shown in FIG. 14 means thatthe same amount of correction is used for sides having the identicalidentification data (188 in FIG. 14).

The processing of step 163 in the flowchart shown in FIG. 12 is asimilar step to the inspection step (step 23 in the flowchart shown inFIG. 2) described with reference to FIG. 8. Specifically, in step 163,evaluation points of a figure element are compared with evaluationpoints of a projected image of the figure element to inspect deformationof the projected image due to the optical proximity effect in order todetermine the conformity in shape between the projected image and thefigure element.

The method for manufacturing a reticle according to the secondembodiment includes the steps shown in FIG. 1, i.e., the steps ofcreating design data of a metal thin-film pattern on a reticle, checkingthe design data, generating figure data for forming a corrected metalthin-film pattern on the reticle by optical proximity effect correction,checking the optical proximity effect, forming an exposure pattern,checking the line width of the exposure pattern, i.e., the resistpattern, and forming a metal thin-film pattern by etching. The step ofgenerating figure data for forming a metal thin-film pattern by opticalproximity effect correction includes the steps shown in FIG. 12, i.e.,the step of performing initial processing on design data, extracting agroup of figure-element sides, assigning identification data, setting afigure element group, assigning identification data, estimating theoptical proximity effect, generating a corrected figure, performinginspection, and configuring figure data by distributing a correctedfigure element.

According to the method for manufacturing the reticle according to thesecond embodiment, therefore, the time required for manufacturing thereticle can be reduced. This is because the time for generating figuredata for a metal thin-film pattern on the reticle is reduced.

Optical proximity effect correction was performed on design dataincluded in a region of about 264 μm×210 μm on a reticle according tothe flowchart shown in FIG. 12. As a result, the number offigure-element sides for which it was determined that estimation of thecorrection was necessary, as described with reference to FIG. 14, was1,089 out of 129,582 figure-element sides. It took ten seconds toidentify the figure-element sides for which it was determined thatestimation of the correction was necessary from classifiedidentification data by searching and sorting. It further took tenseconds to compute a corrected-figure-element side with respect to thefigure-element sides. On the other hand, it took 20 minutes, or 1,200seconds, to compute a corrected-figure-element side with respect to allfigure-element sides without identifying the figure-element sides forwhich it was determined that estimation of the correction was necessary.Therefore, according to flowchart shown in FIG. 12, the figure data canbe produced 60 times faster than normal.

According to the method for manufacturing the reticle according to thesecond embodiment, furthermore, the time for manufacturing a reticle canbe reduced even if a smaller grid is used as the grid of the figuredata. According to the method for manufacturing a reticle according tothe second embodiment, therefore, a reticle having a high-accuracypattern can also be manufactured.

Third Embodiment

A method for manufacturing a semiconductor device according to a thirdembodiment of the present invention using the reticle manufactured inthe first or second embodiment will be described with reference to FIG.17.

FIG. 17 is an illustration showing a process for forming a resistpattern on a semiconductor substrate using the reticle manufactured inthe first or second embodiment, and a process for forming a metal wiringpattern on the semiconductor substrate by etching.

Referring to FIG. 17, the process for forming a resist pattern on asemiconductor substrate is performed by the following procedure: first,a metal layer 214 is deposited on a semiconductor substrate 215, and iscoated with a resist 213. Then, a light 210 is applied to a reticle 211,and light transmitting the reticle 211 is focused by a projector lens212 to expose the resist 213 to light. Layers 217 with the resist 213exposed to light are shown in cross-section. Then, a resist 216 that iscured by exposure is left and the unnecessary resist 213 is removed toform a resist pattern. Layers 218 with the unnecessary resist beingremoved are shown in cross-section.

Then, the process for forming a metal wiring pattern on thesemiconductor substrate by etching is performed by the followingprocedure: first, a pattern on the metal layer 214 is formed byanisotropic etching using the resist pattern as a mask. Layers 219 afteretching are shown in cross-section. Then, the resist pattern is removed,thereby obtaining layers 220 in cross-section with the resist patternbeing removed.

According to the method for manufacturing a semiconductor deviceaccording to the third embodiment, therefore, the reticle manufacturedin the first embodiment or the reticle manufactured in the secondembodiment is used to form a metal layer pattern, thus allowing forhigh-accuracy metal patterning.

1. A manufacturing method for a photomask based on design dataindicating plurality of first figure elements comprising the steps of;extracting first data from design data indicating a first figureelement; assigning identical first identification data to a identicalfirst data indicating the identical shape of first figure element;establishing a region based on the first figure element; recognizing afirst figure element group in the region by the identical firstidentification data; configuring a first data group indicating the firstfigure element group being in the region; assigning identical secondidentification data to a identical first data group; estimating ainfluence of an optical proximity effect on the first figure elementgroup; generating second data indicating a second figure element forcompensating the influence of the optical proximity effect on the firstfigure element group; configuring figure data indicating plurality ofsecond figure elements by assigning identical second data to theidentical first data being included in the identical first data group inthe region, the identical first data group having identical secondidentification data; forming photomask patterns on the photomask usingthe figure data.